The invention relates to an embossing foil such as a hot embossing foil.
Embossing foils may be used for example in the production of documents such as credit cards, identity cards and the like, and a typical form of an embossing foil, as is to be found for example in DE 29 16 723 C2, is in the form of a laminate comprising a succession of a backing foil, an optional separating layer, a transparent cover lacquer layer, a decorative layer and a foundation layer.
As however the above-indicated embossing foil is only decorated on one side, the production of articles which each have a decorative effect on both of their sides requires the use of two such embossing foils. The two embossing foils which are independent of each other must be fed to the article to be decorated therewith, in precisely the correct position. However, that can be a difficult and complicated matter in particular if the two embossing foils are for example of such a nature that they have different stretch properties from each other. A considerable amount of expenditure is also required in that situation in order to ensure not only that the two embossing foils with their decorative effects are fed to the article to be decorated therewith in precisely the correct position, but also to ensure that, during the embossing operation, the two embossing foils are also passed to an embossing station which is provided for that purpose, in precisely the correct positions relative to each other. That operation requires high-precision equipment as well as a not inconsiderable amount of time, in order to produce articles which are decorated on both sides in that way.
A brochure from Leonhard Kurz GmbH & Co, of the Federal Republic of Germany, entitled `Das Pragen auf Kunststoffen`, page 18, discloses what is referred to as `counter-embossing`, involving embossing a highly transparent substrate from the rear thereof. That procedure involves the use of special embossing foils which have their decorative layer of such a nature that the decoration faces away from the backing foil. In addition, articles which are embossed by a counter-embossing process may then also be covered on their rear with a coloured lacquer, or may have material injected on the back thereof, with the embossed image still remaining visible. A serious disadvantage of such a procedure is that the embossing can easily be damaged, both when applying the coloured lacquer to the back of the article and also when carrying out the rear injection operation. Particularly in the latter case, the relatively high temperature involved can give rise to the risk of distortion or peeling of the decorative layer of the counter-foil, due to the lacquer to be applied to the back of the article. In addition double-sided decoration has not been achieved hitherto in the counter-embossing process with an embossing foil.